/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.context.request;

import org.apache.log4j.Logger;
import org.apache.log4j.NDC;
import org.springframework.ui.ModelMap;

/**
 * Request logging interceptor that adds a request context message to the
 * Log4J nested diagnostic context (NDC) before the request is processed,
 * removing it again after the request is processed.
 *
 * @author Juergen Hoeller
 * @see org.apache.log4j.NDC#push(String)
 * @see org.apache.log4j.NDC#pop()
 * @since 2.5
 */
public class Log4jNestedDiagnosticContextInterceptor implements AsyncWebRequestInterceptor {

    /**
     * Logger available to subclasses
     */
    protected final Logger log4jLogger = Logger.getLogger(getClass());

    private boolean includeClientInfo = false;


    /**
     * Set whether or not the session id and user name should be included
     * in the log message.
     */
    public void setIncludeClientInfo(boolean includeClientInfo) {
        this.includeClientInfo = includeClientInfo;
    }

    /**
     * Return whether or not the session id and user name should be included
     * in the log message.
     */
    protected boolean isIncludeClientInfo() {
        return this.includeClientInfo;
    }


    /**
     * Adds a message the Log4J NDC before the request is processed.
     */
    public void preHandle(WebRequest request) throws Exception {
        NDC.push(getNestedDiagnosticContextMessage(request));
    }

    /**
     * Determine the message to be pushed onto the Log4J nested diagnostic context.
     * <p>Default is the request object's {@code getDescription} result.
     *
     * @param request current HTTP request
     * @return the message to be pushed onto the Log4J NDC
     * @see WebRequest#getDescription
     * @see #isIncludeClientInfo()
     */
    protected String getNestedDiagnosticContextMessage(WebRequest request) {
        return request.getDescription(isIncludeClientInfo());
    }

    public void postHandle(WebRequest request, ModelMap model) throws Exception {
    }

    /**
     * Removes the log message from the Log4J NDC after the request is processed.
     */
    public void afterCompletion(WebRequest request, Exception ex) throws Exception {
        NDC.pop();
        if (NDC.getDepth() == 0) {
            NDC.remove();
        }
    }

    /**
     * Removes the log message from the Log4J NDC when the processing thread is
     * exited after the start of asynchronous request handling.
     */
    public void afterConcurrentHandlingStarted(WebRequest request) {
        NDC.pop();
        if (NDC.getDepth() == 0) {
            NDC.remove();
        }
    }

}
